edit numbers in red to change formula either temporarily or save for them to become permanent (but please save your own copy if you want to edit someone else's recipe) as well as to change the final dough quantity.
numbers in green underlined give you the quantities of different ingredients.
For the bread baking recipes this calculator is based on the baker's percentage system which essentially means every other ingredient is expressed as a percentage of the main flour, the main flour being 100%.
However in this iteration for hydration account is also taken of total water to total flour ratio, in other words these calcualtions include water and flour in any starter and preferment as well as that in final mix.
related documents - "How to look after your starter"